1. Field of the Invention
The teachings herein relate to gas turbine engines, and in particular, to a pressurized evaporative cooler system for gas turbine inlet cooling.
2. Description of the Related Art
A typical evaporative cooling system for a gas turbine engine is located in an inlet filter house for the gas turbine and is situated downstream of filter elements. The function of the evaporative cooler system is to increase power output from the engine by cooling the inlet air to the machine through evaporation of water. A typical gas turbine evaporative cooler module includes: an outer evaporative cooler shell; evaporative cooling media pad; water distribution piping and a sump. Embodiments of water distribution and collection systems supply the media with water required for evaporative cooling. Some embodiments further include a drift eliminator system downstream of the evaporative cooler system to prevent any water carryover from the media into the gas turbine engine.
In a conventional evaporative cooler system water flows over the evaporative cooler media from the top of the media pad to the bottom. This water saturates the media from top to bottom. Ambient air that is filtered via inlet filters flows through the evaporative cooler media and thus the water evaporates. This causes the ambient air to cool prior to entering the turbine. Water that does not evaporate in the media trickles through the porous media pad and collects in the sump at the bottom of the media. This water is re-circulated through the media.
While use of an evaporative cooling system increases efficiency of the gas turbine, the placement of the system and other components in front of the inlet of the gas turbine causes a pressure drop that creates a load on the turbine.
Typical values of gas turbine intake pressure drop vary from one inch of water column to six inches of water column. This intake resistance reduces power output from a gas turbine. Typically, one inch of inlet pressure drop results in 1.0 to 2.0 MW power output losses for a commercial size gas turbine engine. If the pressure drop across the inlet filter house can be reduced then the gas turbine engine could generate greater power.
FIG. 1 depicts a typical prior art gas turbine intake filtration system with evaporative cooler module downstream of the filter elements. In addition, an illustration of the evaporative cooler media and side view of the evaporative cooler system is provided. The filtration module in front of the evaporative cooler typically includes a plurality of air filters.
FIG. 2 provides a three-dimensional (3D) view of a prior art evaporative cooler system with evaporative cooler media. Downstream of the media, the drift eliminators are shown which remove any water that potentially carries beyond the media. FIG. 3 is a high level schematic depicting aspects of the prior art evaporative cooling system showing a mechanism of water distribution, which is from the top onto the media. This illustration provides a detailed view of evaporative cooler media which shows water flow from the top and sideways airflow.
Accordingly, what are needed are techniques for providing inlet cooling to a gas turbine while limiting, reducing or eliminating the load created by prior art cooling systems, such as the techniques disclosed herein.